Make the checkbox in settings control the radio buttons in the drawer, to demonstrate how to link s…

sky/examples/stocks2/lib/stock_app.dart

Index: sky/examples/stocks2/lib/stock_app.dart
diff --git a/sky/examples/stocks2/lib/stock_app.dart b/sky/examples/stocks2/lib/stock_app.dart
index 7f319ec0c4dfbd9da8766055ddaf57aaacc3c0d1..1d7c2cf56bdae02756c7a41ff3132bde83587ca4 100644
--- a/sky/examples/stocks2/lib/stock_app.dart
+++ b/sky/examples/stocks2/lib/stock_app.dart
@@ -16,19 +16,41 @@ import 'stock_settings.dart';
 
 class StocksApp extends App {
 
+  NavigationState _navigationState;
   StocksApp() {
     _navigationState = new NavigationState([
       new Route(
         name: '/', 
-        builder: (navigator, route) => new StockHome(navigator, route, _stocks)
+        builder: (navigator, route) => new StockHome(navigator, _stocks, stockMode, modeUpdater)
       ),
       new Route(
         name: '/settings',
-        builder: (navigator, route) => new StockSettings(navigator)
+        builder: (navigator, route) => new StockSettings(navigator, stockMode, settingsUpdater)
       ),
     ]);
   }
 
+  void onBack() {
+    setState(() {
+      _navigationState.pop();
+    });
+    // TODO(jackson): Need a way to invoke default back behavior here
+  }
+
+  StockMode stockMode = StockMode.optimistic;
+  void modeUpdater(StockMode value) {
+    setState(() {
+      stockMode = value;
+    });
+  }
+  void settingsUpdater({StockMode mode}) {
+    setState(() {
+      if (mode != null)
+        stockMode = mode;
+    });
+  }
+
+  final List<Stock> _stocks = [];
   void didMount() {
     super.didMount();
     new StockDataFetcher((StockData data) {
@@ -38,16 +60,6 @@ class StocksApp extends App {
     });
   }
 
-  final List<Stock> _stocks = [];
-  NavigationState _navigationState;
-
-  void onBack() {
-    setState(() {
-      _navigationState.pop();
-    });
-    // TODO(jackson): Need a way to invoke default back behavior here
-  }
-
   Widget build() {
     return new Theme(
       data: new ThemeData.light(